Wireless power transmitter, wireless power receiver, and control methods thereof

ABSTRACT

A wireless power transmitter configured to transmit power to a wireless power receiver and a method for controlling the wireless power transmitted are provided. The method includes applying a detection power for detecting a change in a load impedance of the wireless power transmitter caused by a placement of the wireless power receiver, detecting the change in the load impedance of the wireless power transmitter, receiving a first signal from the wireless power receiver, determining whether a reception intensity of the first signal is greater than a threshold, and transmitting a second signal to the wireless power receiver based on detecting the change in the load impedance and determining whether the reception intensity of the first signal is greater than the threshold.

PRIORITY

This application is a Continuation Application of, and claims priorityunder 35 U.S.C. §120 to, U.S. patent application Ser. No. 14/223,147,which was filed in the U.S. Patent and Trademark Office on Mar. 24,2014, which claims priority under 35 U.S.C. §119(a) to Korean PatentApplication Serial Nos. 10-2013-0031180, 10-2013-0050128,10-2013-0052761, and 10-2013-0053450, which were filed in the KoreanIntellectual Property Office on Mar. 22, 2013, May 3, 2013, May 9, 2013,and May 10, 2013, respectively, the entire content of each of which isincorporated herein by reference.

BACKGROUND 1. Field of the Invention

The present invention generally relates to a wireless power transmitter,a wireless power receiver, and control methods thereof, and moreparticularly, to a wireless power transmitter, a wireless powerreceiver, and control methods thereof, which can wirelesslytransmit/receive charging power.

2. Description of the Related Art

Mobile terminals such as a mobile phone, a Personal Digital Assistant(PDA) and the like are driven by rechargeable batteries, and the batteryof the mobile terminal is charged through supplied electronic energy byusing a separate charging apparatus. In general, separate contactterminals are arranged outside of the charging apparatus and thebattery, and the charging apparatus and the battery are electricallyconnected to each other through contact between the contact terminals.

However, since the contact terminals outwardly protrude in such acontact type charging scheme, the contact terminals are easilycontaminated by rogue substances and thus the battery charging may notbe correctly performed. Further, the battery charging may also not becorrectly performed in a case where the contact terminal is exposed tomoisture.

Recently, a wireless charging or a non-contact charging technology hasbeen developed and used for electronic devices to solve theabove-mentioned problem.

Such a wireless charging technology employs wireless powertransmission/reception, and corresponds to, for example, a system inwhich a battery can be automatically charged if the battery is laid on acharging pad without the need of connecting the mobile phone to aseparate charging connector. In general, electronic products arewirelessly charged through the wireless charging technology, and theportability of electronic devices can be increased since there is noneed to provide a wired charging apparatus. Therefore, technologiesrelated to the wireless charging technology are expected to besignificantly developed in the coming age of electric cars.

The wireless charging technology largely includes an electromagneticinduction scheme using a coil, a resonance scheme using a resonance, andan RF/microwave radiation scheme converting electrical energy tomicrowaves and then transmitting the microwaves.

It is considered up to now that the electromagnetic induction scheme ismainstream, but it is expected all electronic products will bewirelessly charged, anytime and anywhere, without a wire in the nearfuture on the strength of recent successful experiments for wirelesslytransmitting power to a destination spaced away by dozens of metersthrough the use of microwaves.

A power transmission method through electromagnetic inductioncorresponds to a scheme of transmitting electric power between a firstcoil and a second coil. When a magnet is moved in a coil, an inductioncurrent occurs. By using the induction current, a magnetic field isgenerated at a transferring end, and electric current is inducedaccording to a change of the magnetic field so as to create energy at areception end. This phenomenon is referred to as magnetic induction, andthe electric power transmission method using magnetic induction has ahigh energy transmission efficiency.

With respect to the resonance scheme, electricity is wirelesslytransferred using an electric power transmission principle of theresonance scheme based on a coupled mode theory even if a device to becharged is separated from a charging device by several meters. Awireless charging system employs a concept in physics that resonance isthe tendency in which when a tuning fork oscillates at a particularfrequency, a wine glass next to the tuning fork oscillates at the samefrequency. Similarly, an electromagnetic wave containing electricalenergy can be made to resonate, and resonated electrical energy isdirectly transferred only when there is a receiving device having theresonance frequency present. The remaining electrical energy which isnot used is reabsorbed into an electromagnetic field instead of beingspread in the air, so that the electrical energy does not affectsurrounding machines or people, unlike other electromagnetic waves.

Meanwhile, research on a wireless charging method is currently beingconducted, but standards for a wireless charging order, a search for awireless power transmitting unit/receiving unit, selection of acommunication frequency between the wireless power transmittingunit/receiving unit, a wireless power control, selection of a matchingcircuit, and communication time distribution to each wireless powerreceiving unit in one charging cycle, and the like, have not yet beenproposed. Particularly, there is a need for a standard for aconfiguration and a procedure in which the wireless power receiving unitselects the wireless power transmitting unit to receive wireless power.

Specifically, there is a need to develop a technology which, when thewireless power transmitting unit has a communication connection with awireless power receiving unit arranged outside of a charging range,excludes the corresponding wireless power receiving unit.

SUMMARY

The present invention has been made to solve the above problems anddisadvantages, and to provide at least the advantages described below.

Accordingly, an aspect of the present invention provides a wirelesspower transmitting unit and a control method thereof which determine awireless power receiving unit forming a cross-connection and exclude thedetermined wireless power receiving unit. Another aspect of the presentinvention provides a wireless power receiving unit and a control methodthereof in which a wireless power transmitting unit determines awireless power receiving unit forming a cross-connection.

In accordance with an aspect of the present invention, a method forcontrolling a wireless power transmitter configured to transmit power toa wireless power receiver is provided. The method includes applying adetection power for detecting a change in a load impedance of thewireless power transmitter caused by a placement of the wireless powerreceiver, detecting the change in the load impedance of the wirelesspower transmitter, receiving a first signal from the wireless powerreceiver, determining whether a reception intensity of the first signalis greater than a threshold, and transmitting a second signal to thewireless power receiver based on detecting the change in the loadimpedance and determining whether the reception intensity of the firstsignal is greater than the threshold.

In accordance with another aspect of the present invention, a wirelesspower transmitter configured to transmit power to a wireless powerreceiver is provided. The wireless power transmitter includes aresonator configured to transmit wireless power to the wireless powerreceiver, a controller configured to apply a detection power fordetecting a change in a load impedance of the wireless power transmittercaused by a placement of the wireless power receiver to the resonator,and detect the change in the load impedance of the wireless powertransmitter, and a wireless communication unit configured to receive afirst signal from the wireless power receiver, where the controller isfurther configured to determine whether a reception intensity of thefirst signal is greater than a threshold, and control the wirelesscommunication unit to transmit a second signal to the wireless powerreceiver if the first signal is greater than the threshold.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features, and advantages of the presentinvention will be more apparent from the following detailed descriptiontaken in conjunction with the accompanying drawings, in which:

FIG. 1 illustrates a concept for describing overall operations of awireless charging system;

FIG. 2 is a block diagram of a wireless power transmitting unit and awireless power receiving unit according to an embodiment of the presentinvention;

FIG. 3 is a block diagram illustrating in detail a wireless powertransmitting unit and a wireless power receiving unit according to anembodiment of the present invention;

FIG. 4 is a flow diagram illustrating operations of a wireless powertransmitting unit and a wireless power receiving unit according to anembodiment of the present invention;

FIG. 5 is a flowchart illustrating operations of the wireless powertransmitting unit and the wireless power receiving unit according toanother embodiment of the present invention;

FIG. 6 is a graph on an x axis of an amount of power applied by awireless power transmitting unit;

FIG. 7 is a flowchart illustrating a control method of a wireless powertransmitting unit according to an embodiment of the present invention;

FIG. 8 is a graph on an x axis of an amount of power applied by awireless power transmitting unit according to the embodiment of FIG. 7;

FIG. 9 is a flowchart illustrating a control method of a wireless powertransmitting unit according to an embodiment of the present invention;

FIG. 10 is a graph on an x axis of an amount of power applied by awireless power transmitting unit according to the embodiment of FIG. 9;

FIG. 11 is a block diagram of a wireless power transmitting unit and awireless power receiving unit according to an embodiment of the presentinvention;

FIG. 12A is a flowchart illustrating a control method of a wirelesspower receiving unit according to an embodiment of the presentinvention;

FIG. 12B is a flowchart for describing a control method of a wirelesspower transmitting unit according to an embodiment of the presentinvention;

FIG. 13 is a flowchart illustrating operations of a wireless powertransmitting unit and a wireless power receiving unit according to anembodiment of the present invention;

FIG. 14 is a block diagram of a communication unit and peripheralcomponents of a wireless power receiving unit according to an embodimentof the present invention;

FIG. 15A is a flowchart illustrating a control method of a wirelesspower receiving unit according to an embodiment of the presentinvention;

FIG. 15B is a flowchart illustrating a control method of a wirelesspower receiving unit according to an embodiment of the presentinvention;

FIG. 15C is a flowchart illustrating a control method of a wirelesspower transmitting unit according to an embodiment of the presentinvention;

FIGS. 16A and 16B are flowcharts of control methods of a wireless powerreceiving unit and a wireless power transmitting unit according toembodiments of the present invention;

FIG. 17 illustrates a concept for describing cross-communication;

FIG. 18 illustrates a concept for describing an arrangement relationbetween a wireless power transmitting unit and a wireless powerreceiving unit;

FIG. 19 is a flowchart illustrating a method of determining across-connected wireless power receiving unit according to an embodimentof the present invention;

FIG. 20A is a graph showing a change in transmission power of a wirelesspower transmitting unit according to an embodiment of the presentinvention;

FIG. 20B is a graph showing a change in a voltage of a wireless powerreceiving unit according to an embodiment of the present invention;

FIG. 21 is a flowchart illustrating a method of determining across-connected wireless power receiving unit according to anotherembodiment of the present invention;

FIG. 22 is a graph showing intensities of signals from wireless powerreceiving units according to an embodiment of the present invention; and

FIG. 23 is a flowchart illustrating a method of determining across-connected wireless power receiving unit according to anotherembodiment of the present invention.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE PRESENT INVENTION

Hereinafter, various embodiments of the present invention will bedescribed in detail with reference to the accompanying drawings. Itshould be noted that the same components of the drawings are designatedby the same reference numeral throughout the figures. In the followingdescription of the present invention, a detailed description of knownfunctions and configurations incorporated herein will be omitted when itmay make the subject matter of the present disclosure unclear.

FIG. 1 illustrates a concept describing general operations of a wirelesscharging system. As illustrated in FIG. 1, the wireless charging systemincludes a wireless power transmitting unit 100 and one or more wirelesspower receiving units 110-1, 110-2, . . . , and 110-n.

The wireless power transmitting unit 100 wirelessly transmits power 1-1,1-2, . . . , and 1-n to the one or more wireless power receiving units110-1, 110-2, . . . , and 110-n, respectively. More specifically, thewireless power transmitting unit 100 may wirelessly transmit power 1-1,1-2, . . . , and 1-n to only wireless power receiving units which havebeen authenticated through a predetermined authentication procedure.

The wireless power transmitting unit 100 forms an electrical connectionwith the wireless power receiving units 110-1, 110-2, . . . , and 110-n.For example, the wireless power transmitting unit 100 transmits wirelesspower in an electromagnetic wave form to the wireless power receivingunits 110-1, 110-2, . . . , and 110-n.

Meanwhile, the wireless power transmitting unit 100 may performbidirectional communication with the wireless power receiving units110-1, 110-2, . . . , and 110-n. The wireless power transmitting unit100 and the wireless power receiving units 110-1, 110-2, . . . , and110-n may process or transmit packets 2-1, 2-2, . . . , and 2-nincluding predetermined frames. The frames will be described below inmore detail. Particularly, the wireless power receiving units may be amobile communication terminal, a PDA, a PMP, a smart phone, and thelike.

The wireless power transmitting unit 100 wirelessly provides electricpower to a plurality of wireless power receiving units 110-1, 110-2, . .. , and 110-n. For example, the wireless power transmitting unit 100transmits electric power to the one or more wireless power receivingunits 110-1, 110-2, . . . , and 110-n through a resonance scheme. Whenthe wireless power transmitting unit 100 adopts the resonance scheme, itis preferable that a distance between the wireless power transmittingunit 100 and the one or more wireless power receiving units 110-1,110-2, . . . , and 110-n is less than or equal to m. Further, when thewireless power transmitting unit 100 adopts the electromagneticinduction scheme, it is preferable that a distance between the wirelesspower transmitting unit 100 and the plurality of wireless powerreceiving units 110-1, 110-2, . . . , and 110-n is less than or equal to10 cm.

The wireless power receiving units 110-1, 110-2, . . . , and 110-nreceive wireless power from the wireless power transmitting unit 100 tocharge batteries therein. Further, the wireless power receiving units110-1, 110, -2, 110-2, . . . , and 110-n transmit a signal forrequesting wireless power transmission, information required forwireless power reception, state information of the wireless powerreceiving unit, or control information of the wireless powertransmitting unit 100 to the wireless power transmitting unit 100.Information on the transmitted signal will be described below in moredetail.

Further, the wireless power receiving units 110-1, 110-2, . . . , and110-n may transmit a message indicating a charging state of each of thewireless power receiving units 110-1, 110-2, . . . , and 110-n to thewireless power transmitting unit 100.

The wireless power transmitting unit 100 may include a display meanssuch as a display, and displays a state of each of the wireless powerreceiving units 110-1, 110-2, and 110-n based on the message receivedfrom each of the wireless power receiving units 110-1, 110-2, . . . ,and 110-n. Further, the wireless power transmitting unit 100 may alsodisplay a time expected to be spent until each of the wireless powerreceiving units 110-1, 110-2, . . . , and 110-n is completely charged.

The wireless power transmitting unit 100 may transmit a control signalfor disabling a wireless charging function to each of the wireless powerreceiving units 110-1, 110-2, . . . , and 110-n. The wireless powerreceiving units having received the disabled control signal of thewireless charging function from the wireless power transmitting unit 100disable the wireless charging function.

FIG. 2 is a block diagram illustrating a wireless power transmittingunit and a wireless power receiving unit according to an embodiment ofthe present invention.

As illustrated in FIG. 2, the wireless power transmitting unit 200includes a power transmitter 211, a controller 212 and a communicationunit 213. Further, the wireless power receiving unit 250 includes apower receiver 251, a controller 252 and a communication unit 253.

The power transmitter 211 supplies power which is required by thewireless power transmitting unit 200, and wirelessly provides power tothe wireless power receiving unit 250. Here, the power transmitter 211may provide the power in a form of alternate current (AC) waves, andalso may convert direct current (DC) waves into the AC waves by using aninverter while providing the power in a form of DC waves, so as toprovide the power in the form of AC waves. The power transmitter 211 maybe implemented in a form of an embedded battery or in a form of a powerreceiving interface so as to receive the power from outside thereof andsupply the power to the other components. It will be easily understoodby those skilled in the art that the power transmitter 211 is notlimited as long as it can supply power of constant AC waves.

In addition, the power transmitter 211 may supply the AC waves to thewireless power receiving unit 250 in a form of electromagnetic waves.The power transmitter 211 may further include a resonant circuit,resulting in transmission or reception of predetermined electromagneticwaves. When the power transmitter 211 is implemented by the resonantcircuit, inductance L of a loop coil of the resonant circuit may bechanged. It will be easily understood by those skilled in the art thatthe power transmitter 211 is not limited as long as it can transmit andreceive the electromagnetic waves.

The controller 212 controls overall operations of the wireless powertransmitting unit 200. The controller 212 may control overall operationsof the wireless power transmitting unit 200 by using an algorithm, aprogram, or an application which is required for a control and read froma storage unit (not shown). The controller 212 may be implemented in aform of a CPU, a microprocessor, a mini computer and the like. Operationof the controller 212 will be described below in detail.

The communication unit 213 communicates with the wireless powerreceiving unit 250 in a specific manner. The communication unit 213communicates with a communication unit 253 of the wireless powerreceiving unit 250 by using, for example, a Near Field Communication(NFC) scheme, a Zigbee communication scheme, an infrared raycommunication scheme, a visible ray communication scheme, a Bluetoothcommunication scheme, a Bluetooth Low Energy (BLE) scheme and the like.In addition, the communication unit 213 may use a CSMA/CA algorithm.Meanwhile, the above mentioned communication schemes are only examples,and the scope of the present invention is not limited by a specificcommunication scheme which is performed by the communication unit 213.

Furthermore, the communication unit 213 may transmit a signal forproviding information of the wireless power transmitting unit 200. Here,the communication unit 213 may unicast, multicast, or broadcast thesignal. Table 1 shows a data structure of a signal transmitted from thewireless power transmitting unit 200 according to an embodiment of thepresent invention. The wireless power transmitting unit 200 may transmita signal having the following frame on every preset period, and thesignal may be referred to as a notice signal hereinafter.

TABLE 1 RX to protocol sequence Report(schedule Number of frame typeversion number network ID mask) Reserved Rx Notice 4 bit 1 Byte 1 Byte 1Byte 5 bit 3 bit

A frame type in Table 1 refers to to a field indicating a type ofsignal, and indicates that a corresponding signal is a notice signal. Aprotocol version field is a field indicating a type of protocol of acommunication scheme and may be allocated, for example, 4 bits. Asequence number field is a field indicating a sequential order of thecorresponding signal and may be allocated, for example, 1 byte. Forexample, the sequence number may increase by one for each signaltransmission/reception step. A network ID field is a field indicating anetwork ID of the wireless power transmitting unit 200 and may beallocated, for example, 1 byte. An Rx to Report (schedule mask) field isa field indicating wireless power receiving units for providing a reportto the wireless power transmitting unit 200 and may be allocated, forexample, 1 byte. Table 2 shows the Rx to Report (schedule mask) fieldaccording to an embodiment of the present invention.

TABLE 2 Rx to Report (schedule mask) Rx1 Rx2 Rx3 Rx4 Rx5 Rx6 Rx7 Rx8 1 00 0 0 1 1 1

In Table 2, Rx1 to Rx8 may correspond to first to eighth wireless powerreceiving units (PRU#1˜PRU#8). The Rx to Report (schedule mask) fieldmay be implemented such that the wireless power receiving unit having aschedule mask number of 1 provides a report, whereas the wireless powerreceiving unit having a schedule mask number of 0 does not provide areport.

A reserved field is a field reserved for being used in the future andmay be allocated, for example, 5 bytes. A number of Rx field is a fieldindicating a number of wireless power receiving units located near thewireless power transmitting unit 200 and may be allocated, for example,3 bits.

The communication unit 213 receives power information from the wirelesspower receiving unit 250. Here, the power information may include atleast one of a capacity of the wireless power receiving unit 250, aresidual battery amount, a number of times of charges, an amount of use,a battery capacity, and a proportion of the battery.

Further, the communication unit 213 may transmit a signal of controllinga charging function in order to control the charging function of thewireless power receiving unit 250. The signal of controlling thecharging function is a control signal of controlling the wireless powerreceiver 251 of the specific wireless power receiving unit 250 so as toenable or disable the charging function. More specifically, the powerinformation may include information on an insertion of a wirelesscharging terminal, a transition from a Stand Alone (SA) mode to a NonStand Alone (NSA) mode, error state release and the like.

The communication unit 213 may receive a signal from another wirelesspower transmitting unit (not shown) as well as the wireless powerreceiving unit 250. For example, the communication unit 213 may receivea notice signal of the frame in the above mentioned Table 1 from anotherwireless power transmitting unit.

Meanwhile, in FIG. 2, it is shown that the power transmitter 211 and thecommunication unit 213 are configured as different hardware and thewireless power transmitting unit 200 communicates in an out-band manner,but this is only an example. In the present invention, the powertransmitter 211 and the communication unit 213 may be implemented as asingle hardware device so that the wireless power transmitting unit 200performs communication in an in-band manner.

The wireless power transmitting unit 200 and the wireless powerreceiving unit 250 transmit and receive various signals. Accordingly,the wireless power receiving unit 250 enters a wireless power networkwhich is managed by the wireless power transmitting unit 200 andperforms a charging process through wireless power transmission andreception. The above mentioned process will be described below in moredetail.

FIG. 3 is a block diagram illustrating in detail the wireless powertransmitting unit and the wireless power receiving unit according to theembodiment of the present invention.

As illustrated in FIG. 3, the wireless power transmitting unit 200includes the power transmitter 211, the controller/communication unit(or MCU & Out-of-band Signaling unit) 212/213, a driver (or power supplyunit) 214, an amplifier 215, and a matching unit 216. The wireless powerreceiving unit 250 includes the power receiver 251, thecontroller/communication unit (or MCU & Out-of-band Signaling unit)252/253, a rectifier 254, a DC/DC converter 255, a switching unit 256,and a loading unit 257.

The driver 214 outputs DC power having a preset voltage value. Thevoltage value of the DC power output by the driver 214 may be controlledby the controller/communication unit 212/213.

The DC power output from the driver 214 is output to the amplifier 215.The amplifier 215 amplifies the DC power by a preset gain. Further, theamplifier 215 converts DC power to AC power based on a signal input fromthe controller/communication unit 212/213. Accordingly, the amplifier215 outputs AC power to the matching unit 216.

The matching unit 216 performs impedance matching. For example, thematching unit 216 adjusts impedance viewed from the matching unit 316 tocontrol output power to be high efficiency or high output power. Thematching unit 216 adjusts impedance based on a control of thecontroller/communication unit 212/213. The matching unit 216 may includeat least one of a coil and a capacitor. The controller/communicationunit 212/213 controls a connection state with at least one of the coiland the capacitor, and accordingly, performs impedance matching.

The power transmitter 211 transmits input AC power to the power receiver251. The power transmitter 211 and the power receiver 251 may beimplemented by resonant circuits having the same resonance frequency.For example, the resonance frequency may be determined as 6.78 MHz.

Meanwhile, the controller/communication unit 212/213 communicates withthe controller/communication unit 252/253 of the wireless powerreceiving unit 350, and performs communication, for example, with abi-directional 2.4 GHz frequency.

The power receiver 251 receives charging power.

The rectifier 254 rectifies wireless power received by the powerreceiver 251 in the form of DC power, and may be implemented in a formof bridge diode. The DC/DC converter 255 converts the rectified currentinto a predetermined gain. For example, the DC/DC converter 255 convertsthe rectified electric current so that a voltage of an output end 259becomes 5V. Meanwhile, a minimum value and a maximum value of thevoltage which can be applied may be preset for a front end 258 of theDC/DC converter 255.

The switching unit 256 connects the DC/DC converter 255 and the loadingunit 257. The switching unit 256 maintains an on/off state under acontrol of the controller 252. When the switching unit 256 is in the onstate, the loading unit 257 stores converted power which is input fromthe DC/DC converter 255.

FIG. 4 is a flow diagram illustrating operations of the wireless powertransmitting unit and the wireless power receiving unit according to anembodiment of the present invention. As illustrated in FIG. 4, awireless power transmitting unit 400 applies power in step S401. Whenthe power is applied, the wireless power transmitting unit 400configures an environment in S402.

The wireless power transmitting unit 400 enters a power saving mode instep S403. In the power saving mode, the wireless power transmittingunit 400 may apply different types of power beacons for detectionaccording to their own periods, which will be described in more detailwith reference to FIG. 6. For example, in FIG. 4, the wireless powertransmitting unit 400 may apply detection power beacons in steps S404and S405 and sizes of power values of the detection power beacons may bedifferent. A part or all of the detection power beacons of steps S404and S405 may have power enough power to drive the communication unit ofthe wireless power receiving unit 450. For example, the wireless powerreceiving unit 450 may drive the communication unit by the part or allof the detection power beacons of steps S404 and S405 to communicatewith the wireless power transmitting unit 400. The above state isreferred to as a null state in step S406.

The wireless power transmitting unit 400 detects a load change by anarrangement of the wireless power receiving unit 450. The wireless powertransmitting unit 400 enters a low power mode in step S409. The lowpower mode will be described in more detail with reference to FIG. 6.Meanwhile, the wireless power receiving unit 450 drives thecommunication unit based on power received from the wireless powertransmitting unit 400 in step S409.

The wireless power receiving unit 450 transmits a Power TransmittingUnit (PTU) searching signal to the wireless power transmitting unit 400in step S410. The wireless power receiving unit 450 may transmit the PTUsearching signal as an advertisement signal based on BLE. The wirelesspower receiving unit 450 may transmit the PTU searching signalperiodically or until a preset time arrives and receives a responsesignal from the wireless power transmitting unit 400.

When receiving the PTU searching signal from the wireless powerreceiving unit 450, the wireless power transmitting unit 400 transmits aPower Receiving Unit (PRU) response signal in step S411. The PRUresponse signal results in a connection between the wireless powertransmitting unit 400 and the wireless power receiving unit 450.

The wireless power receiving unit 450 transmits a PRU static signal instep S412. The PRU static signal may be a signal indicating a state ofthe wireless power receiving unit 450 and which requests joining thewireless power network managed by the wireless power transmitting unit400.

The wireless power transmitting unit 400 transmits a PTU static signalin step S413. The PTU static signal transmitted by the wireless powertransmitting unit 400 may be a signal indicating a capability of thewireless power transmitting unit 400.

When the wireless power transmitting unit 400 and the wireless powerreceiving unit 450 transmit and receive the PRU static signal and thePTU static signal, the wireless power receiving unit 450 periodicallytransmits a PRU dynamic signal in steps S414 and S415. The PRU dynamicsignal includes at least one parameter information measured by thewireless power receiving unit 450. For example, the PRU dynamic signalmay include voltage information of a back end of the rectifier of thewireless power receiving unit 450. The state of the wireless powerreceiving unit 450 is referred to as a boot state in step S407.

The wireless power transmitting unit 400 may enter a power transmissionmode in step S416 and transmits a PRU command signal corresponding to acommand signal to allow the wireless power receiving unit 450 to becharged in step S417. In the power transmission mode, the wireless powertransmitting unit 400 transmits charging power.

The PRU command signal transmitted by the wireless power transmittingunit 400 may include information for enabling/disabling the charging ofthe wireless power receiving unit 450 and permission information. ThePRU command signal may be transmitted when the wireless powertransmitting unit 400 changes the state of the wireless power receivingunit 450 or periodically, for example, a period of 250 ms. The wirelesspower receiving unit 450 may change a configuration according to the PRUcommand signal and transmit the PRU dynamic signal for reporting thestate of the wireless power receiving unit 450 in steps S418 and S419.The PRU dynamic signal transmitted by the wireless power receiving unit450 includes at least one of information on a voltage, a current, astate of the wireless power receiving unit, and temperature. The stateof the wireless power receiving unit 450 is referred to as an on statein step S421.

Meanwhile, the PRU dynamic signal may have a data structure as shown inTable 3 below.

TABLE 3 Field octets description use units optional fields 1 defineswhich mandatory optional fields are populated Vrect 2 voltage at diodemandatory mV output Irect 2 current at diode mandatory mA output Vout 2voltage at optional mV charge/battery port Iout 2 current at optional mAcharge/battery port temperature 1 temperature of PRU optional Deg C.from −40 C. Vrect min dyn 2 Vrect low optional mV limit(dynamic value)Vrect set dyn 2 desired Vrect optional mV (dynamic value) Vrect high dyn2 Vrect high limit optional mV (dynamic value) PRU alert 1 warningsmandatory Bit field RFU(Reserved 3 undefined for Future Use)

The PRU dynamic signal may include at least one of optional fieldinformation, voltage information of the back end of the rectifier of thewireless power receiving unit (‘Vrect’), current information of the backend of the rectifier of the wireless power receiving unit (‘Irect’),voltage information of the back end of the DC/DC converter of thewireless power receiving unit (‘Vout’), current information of the backend of the DC/DC converter of the wireless power receiving unit(‘Iout’), temperature information (‘temperature’), minimum voltage valueinformation of the back end of the rectifier of the wireless powerreceiving unit (‘Vrect min dyn’), optimal voltage value information ofthe back end of the rectifier of the wireless power receiving unit(‘Vrect set dyn’), maximum voltage value information of the back end ofthe rectifier of the wireless power receiving unit (‘Vrect high dyn’),and alert information (‘PRU alert’) as shown in Table 3.

The alert information (‘PRU alert’) may have a data structure as shownin Table 4 below.

TABLE 4 7 6 5 4 3 2 1 0 over over current over charge TA detecttransition restart RFU voltage temperature complete request

The alert information may include over voltage, over current, overtemperature, charge complete, Travel Adapter (TA) detection, SA mode/NSAmode transition, restart request and the like as shown in Table 4.

The wireless power receiving unit 450 receives the PRU command signal toperform the charging. For example, when the wireless power transmittingunit 400 has enough power to charge the wireless power receiving unit450, the wireless power transmitting unit 400 transmits the PRU commandsignal for enabling the charging. Meanwhile, the PRU command signal maybe transmitted whenever the charging state is changed. The PRU commandsignal may be transmitted, for example, every 250 ms, or transmittedwhen a parameter is changed. The PRU command signal may be set to betransmitted within a preset threshold, for example, within one secondeven though the parameter is not changed.

Meanwhile, the wireless power receiving unit 450 detects the generationof errors. The wireless power receiving unit 450 transmits an alertsignal to the wireless power transmitting unit 400 in step S420. Thealert signal may be transmitted as the PRU dynamic signal or a PRU alertsignal. For example, the wireless power receiving unit 450 may transmitthe PRU alert field of Table 3 reflecting an error state to the wirelesspower transmitting unit 400. Alternatively, the wireless power receivingunit 450 may transmit a single PRU alert signal indicating the errorstate to the wireless power transmitting unit 400. When receiving thealert signal, the wireless power transmitting unit 400 may enter a latchfault mode in step S422. The wireless power receiving unit 450 may entera null state in step S423.

FIG. 5 is a flowchart illustrating operations of the wireless powertransmitting unit and the wireless power receiving unit according toanother embodiment of the present invention. A control method of FIG. 5will be described in more detail with reference to FIG. 6. FIG. 6 is agraph on an x axis of a power amount applied by the wireless powertransmitting unit according to the embodiment of FIG. 5.

As illustrated in FIG. 5, the wireless power transmitting unit initiatesthe operation in step S501. Further, the wireless power transmittingunit resets an initial configuration in step S503. The wireless powertransmitting unit enters a power saving mode in step S505. The powersaving mode may correspond to an interval where the wireless powertransmitting unit applies power having different amounts to the powertransmitter. For example, the power saving mode may correspond to aninterval where the wireless power transmitting unit applies second power601 and 602 and third power 611, 612, 613, 614, and 615 to the powertransmitter in FIG. 6. The wireless power transmitting unit mayperiodically apply the second power 601 and 602 according to a secondperiod. When the wireless power transmitting unit applies the secondpower 601 and 602, the application continues for a second period. Thewireless power transmitting unit may periodically apply the third power611, 612, 613, 614, and 615 according to a third period. When thewireless power transmitting unit applies the third power 611, 612, 613,614, and 615, the application continues for the third period. Meanwhile,although it is illustrated that power values of the third power 611,612, 613, 614, and 615 are different from each other, the power valuesof the third power 611, 612, 613, 614, and 615 may be different or thesame.

For example, the wireless power transmitting unit may output the thirdpower 611 and then output the third power 612 having the same size ofthe power amount. As described above, when the wireless powertransmitting unit outputs the third power having the same size, thepower amount of the third power may have a power amount by which asmallest wireless power receiving unit, for example, a wireless powerreceiving unit of a Category 1 can be detected.

The wireless power transmitting unit may output the third power 611 andthen output the third power 612 having a different size of the poweramount. As described above, when the wireless power transmitting unitoutputs the third power having the different size, the power amount ofthe third power may be a power amount by which a wireless powerreceiving unit of a Category 1 to Category 5 can be detected. Forexample, when the third power 611 has a power amount by which a wirelesspower receiving unit of Category 5 can be detected, the third power 612may have a power amount by which a wireless power receiving unit ofCategory 3 can be detected, and the third power 613 may have a poweramount by which a wireless power receiving unit of Category 1 can bedetected.

Meanwhile, the second power 601 and 602 may be power which can drive thewireless power receiving unit. More specifically, the second power 601and 602 may have a power amount which can drive the controller and thecommunication unit of the wireless power receiving unit.

The wireless power transmitting unit applies the second power 601 and602 and the third power 611, 612, 613, 614, and 615 to the powerreceiver according to a second period and a third period, respectively.When the wireless power receiving unit is arranged on the wireless powertransmitting unit, impedance viewed from a point of the wireless powertransmitting unit may be changed. The wireless power transmitting unitdetects a change in the impedance while the second power 601 and 602 andthe third power 611, 612, 613, 614, and 615 are applied. For example,the wireless power transmitting unit may detect the change in theimpedance while the third power 615 is applied. Accordingly, thewireless power transmitting unit may detect an object instead of thewireless receiving unit in step S507. When the object is not detected instep S507, the wireless power transmitting unit returns to step S505 andmaintains a power saving mode in which different power is periodicallyapplied.

Meanwhile, when there is the change in the impedance and thus the objectis detected in step S507, the wireless power transmitting unit enters alow power mode in step S509. The low power mode is a mode in which thewireless power transmitting unit applies driving power having a poweramount by which the controller and the communication unit of thewireless power receiving unit can be driven. For example, in FIG. 6, thewireless power transmitting unit applies driving power 620 to the powertransmitter. The wireless power receiving unit receives the drivingpower 620 to drive the controller and the communication unit. Thewireless power receiving unit performs communication with the wirelesspower transmitting unit according to a predetermined scheme based on thedriving power 620. For example, the wireless power receiving unit maytransmit/receive data required for an authentication and join thewireless power network managed by the wireless power transmitting unitbased on the data. However, when a rogue object (foreign substance, etc)is arranged on the wireless power transmitting unit instead of thewireless power receiving unit, the data transmission/reception cannot beperformed. Accordingly, the wireless power transmitting unit determineswhether the arranged object is the rogue object (or froeign object) instep S511. For example, when the wireless power transmitting unit doesnot receive a response from the object within a preset time, thewireless power transmitting unit determines the object to be the rogueobject.

When the object is determined to be the rogue object in step S511, thewireless power transmitting unit enters a latch fault mode. When theobject is not determined to be the rogue object in step S511, thewireless power transmitting unit performs a joining step in step S519.For example, the wireless power transmitting unit may periodically applyfirst power 631 to 634 according to a first period in FIG. 6. Thewireless power transmitting unit may detect a change in impedance whileapplying the first power. For example, when the rogue object is removed,an impedance change may be detected and the wireless power transmittingunit may determine that the rogue object has been removed.Alternatively, when the rogue object has not been removed, the wirelesspower transmitting unit does not detect an impedance change and maydetermine that the rogue object has not been removed. When the rogueobject has not been removed, the wireless power transmitting unit mayoutput at least one of a lamp and a warning sound to inform a user thata state of the wireless power transmitting unit is an error state.Accordingly, the wireless power transmitting unit may include an outputunit that outputs at least one of the lamp and the warning sound.

When it is determined that the rogue object has not been removed in stepS515, the wireless power transmitting unit returns to step S513 andmaintains the latch fault mode. When it is determined that the rogueobject has been removed in step S515, the wireless power transmittingunit enters the power saving mode again in step S517. For example, thewireless power transmitting unit applies second power 651 and 652 andthird power 661 to 665 of FIG. 6.

As described above, when the rogue object is arranged on the wirelesspower transmitting unit instead of the wireless power receiving unit,the wireless power transmitting unit enters the latch fault mode.Further, the wireless power transmitting unit determines whether toremove the rogue object by checking for an impedance change based on thepower applied in the latch fault mode. That is, a condition of theentrance into the latch fault mode in the embodiment of FIGS. 5 and 6may be the arrangement of the rogue object on the wireless transmittingunit. Meanwhile, the wireless power transmitting unit may have variouslatch fault mode entrance conditions as well as the arrangement of therogue object. For example, the wireless power transmitting unit may becross-connected with the arranged wireless power receiving unit and mayenter the latch fault mode in the above case.

Accordingly, when the cross-connection is generated, the wireless powertransmitting unit is required to return to an initial state and thewireless power receiving unit is required to be removed. The wirelesspower transmitting unit may set the cross-connection by which thewireless power receiving unit arranged on another wireless powertransmitting unit joins the wireless power network as the latch faultmode entrance condition. An operation of the wireless power transmittingunit when the error is generated which includes the cross-connectionwill be described with reference to FIG. 7.

FIG. 7 is a flowchart illustrating a control method of the wirelesspower transmitting unit according to an embodiment of the presentinvention. The control method of FIG. 7 will be described in more detailwith reference to FIG. 8. FIG. 8 is a graph on an x axis of a poweramount applied by the wireless power transmitting unit according to theembodiment of FIG. 7.

The wireless power transmitting unit initiates the operation in stepS701. Further, the wireless power transmitting unit resets an initialconfiguration in step S703. The wireless power transmitting unit entersthe power saving mode again in step S705. The power saving mode may bean interval where the wireless power transmitting unit applies powerhaving different amounts to the power transmitter. For example, thepower saving mode may correspond to an interval where the wireless powertransmitting unit applies second power 801 and 802 and third power 811,812, 813, 814, and 815 to the power transmitter in FIG. 8. The wirelesspower transmitting unit may periodically apply the second power 801 and802 according to a second period. When the wireless power transmittingunit applies the second power 801 and 802, the application continues fora second period. The wireless power transmitting unit may periodicallyapply the third power 811, 812, 813, 814, and 815 according to a thirdperiod. When the wireless power transmitting unit applies the thirdpower 811, 812, 813, 814, and 815, the application continues for thethird period. Meanwhile, although it is illustrated that power values ofthe third power 811, 812, 813, 814, and 815 are different from eachother, the power values of the third power 811, 812, 813, 814, and 815may be different or the same.

Meanwhile, the second power 801 and 802 may be power which can drive thewireless power receiving unit. More specifically, the second power 601and 602 may have a power amount which can drive the controller and thecommunication unit of the wireless power receiving unit.

The wireless power transmitting unit applies the second power 801 and802 and the third power 811, 812, 813, 814, and 815 to the powerreceiver according to a second period and a third period, respectively.When the wireless power receiving unit is arranged on the wireless powertransmitting unit, impedance viewed from a point of the wireless powertransmitting unit may be changed. The wireless power transmitting unitdetects the impedance change while the second power 801 and 802 and thethird power 811, 812, 813, 814, and 815 are applied. For example, thewireless power transmitting unit may detect the impedance change whilethe third power 815 is applied. Accordingly, the wireless powertransmitting unit may detect an object instead of the wireless powerreceiving unit in step S707. When the object is not detected in stepS707, the wireless power transmitting unit returns to step S705 andmaintains the power saving mode in which different power is periodicallyapplied.

Meanwhile, when the impedance is changed and thus the object is detectedin step S707, the wireless power transmitting unit enters the low powermode in step S709. The low power mode is a mode in which the wirelesspower transmitting unit applies driving power having a power amount bywhich the controller and the communication unit of the wireless powerreceiving unit can be driven. For example, in FIG. 8, the wireless powertransmitting unit applies driving power 820 to the power transmitter.The wireless power receiving unit receives the driving power 820 todrive the controller and the communication unit. The wireless powerreceiving unit performs communication with the wireless powertransmitting unit according to a predetermined scheme based on thedriving power 820. For example, the wireless power receiving unit maytransmit/receive data required for an authentication and join thewireless power network managed by the wireless power transmitting unitbased on the data.

Thereafter, the wireless power transmitting unit enters the powertransmission mode in which charging power is transmitted in step S711.For example, the wireless power transmitting unit applies charging power821 and the charging power is transmitted to the wireless powerreceiving unit as illustrated in FIG. 8.

The wireless power transmitting unit determines whether an error isgenerated in the power transmission mode in step S713. The error may bethe arrangement of the rogue object on the wireless power transmittingunit, cross-connection, over voltage, over current, over temperature andthe like. The wireless power transmitting unit may include a sensingunit that measures the over voltage, the over current, the overtemperature and the like. For example, the wireless power transmittingunit measures a voltage or a current at a reference position. When themeasured voltage or current is larger than a threshold, it is determinedthat conditions of the over voltage or the over current are satisfied.Alternatively, the wireless power transmitting unit may include atemperature sensing means and the temperature sensing means measures atemperature at a reference position of the wireless power transmittingunit. When the temperature at the reference position is larger than athreshold, the wireless power transmitting unit determines that acondition of the over temperature is satisfied.

Although it has been illustrated that the error is generated since therogue object is additionally arranged on the wireless power transmittingunit in this embodiment of FIG. 8, such an error is not limited theretoand it will be easily understood by those skilled in the art that thewireless power transmitting unit operates through a similar process withrespect to the arrangement of the rogue object, cross-connection, overvoltage, over current, and over temperature.

When the error is not generated in step S713, the wireless powertransmitting unit returns to step S711 and maintains the powertransmission mode. Meanwhile, when the error is generated in step S713,the wireless power transmitting unit enters the latch fault mode in stepS715. For example, the wireless power transmitting unit applies firstpower 831 to 835 as illustrated in FIG. 8. Further, the wireless powertransmitting unit may output an error generation display including atleast one of a lamp and a warning sound during the latch fault mode.When it is determined that the rogue object has not been removed in stepS717, the wireless power transmitting unit returns to step S715 andmaintains the latch fault mode. Meanwhile, when it is determined thatthe rogue object has been removed in step S717, the wireless powertransmitting unit enters the power saving mode again in step S719. Forexample, the wireless power transmitting unit applies second power 851and 852 and third power 861 to 865 of FIG. 8.

In the above description, the operation in a case where the error isgenerated while the wireless power transmitting unit transmits thecharging power has been discussed. Hereinafter, an operation in a casewhere a plurality of wireless power receiving units on the wirelesspower transmitting unit receive charging power will be described.

FIG. 9 is a flowchart illustrating a control method of the wirelesspower transmitting unit according to an embodiment of the presentinvention. The control method of FIG. 9 will be described in more detailwith reference to FIG. 10. FIG. 10 is a graph on an x axis of a poweramount applied by the wireless power transmitting unit according to theembodiment of FIG. 9.

As illustrated in FIG. 9, the wireless power transmitting unit transmitscharging power to a first wireless power receiving unit in step S901.Further, the wireless power transmitting unit allows a second wirelesspower receiving unit to additionally join the wireless power network instep S903. The wireless power transmitting unit transmits charging powerto the second wireless power receiving unit in step S905. Morespecifically, the wireless power transmitting unit applies a sum of thecharging power required by the first wireless power receiving unit andthe second wireless power receiving unit to the power receiver.

FIG. 10 illustrates an embodiment of steps S901 to S905. For example,the wireless power transmitting unit maintains the power saving mode inwhich second power 1001 and 1002 and third power 1011 to 1015 areapplied. Thereafter, the wireless power transmitting unit detects thefirst wireless power receiving unit and enters the low power mode inwhich a detection power 1020 applied to the first wireless powerreceiving unit to detect is maintained. Next, the wireless powertransmitting unit enters the power transmission mode in which firstcharging power 1030 is applied. The wireless power transmitting unitdetects the second wireless power receiving unit and allows the secondwireless power receiving unit to join the wireless power network.Further, the wireless power transmitting unit applies second chargingpower 1040 having a power amount corresponding to a sum of power amountsrequired by the first wireless power receiving unit and the secondwireless power receiving unit.

Referring back to FIG. 9, the wireless power transmitting unit detectserror generation in step S907 while charging power is transmitted toboth the first and second wireless power receiving units in step S905.As described above, the error may be the arrangement of the rogue objecton the wireless power transmitting unit, cross-connection, over voltage,over current, over temperature, and the like. When the error is notgenerated in step S907, the wireless power transmitting unit returns tostep S905 and maintains the application of the second charging power1040.

Meanwhile, when the error is generated in step S907, the wireless powertransmitting unit enters the latch fault mode in step S909. For example,the wireless power transmitting unit applies first power 1051 to 1055according to a first period in FIG. 10. The wireless power transmittingunit determines whether both the first wireless power receiving unit andthe second wireless power receiving unit have been removed in step S911.For example, the wireless power transmitting unit may detect animpedance change while applying the first power 1051 to 1055. Thewireless power transmitting unit determines whether both the firstwireless power receiving unit and the second wireless power receivingunit have been removed based on whether the impedance is returned to aninitial value.

When it is determined that both the first wireless power receiving unitand the second wireless power receiving unit have been removed in stepS911, the wireless power receiving unit enters the power saving mode instep S913. For example, the wireless power transmitting unit appliessecond power 1061 and 1062 and third power 1071 to 1075 according to asecond period and a third period, respectively.

As described above, even when the wireless power transmitting unitapplies charging power to at least one wireless power receiving unit,the wireless power transmitting unit may determine whether the wirelesspower receiving unit or the rogue object is easily removed when theerror is generated.

FIG. 11 is a block diagram of a wireless power transmitting unit and awireless power receiving unit according to an embodiment of the presentinvention.

A wireless power transmitting unit 1100 includes a communication unit1110, a Power Amplifier (PA) 1120, and a resonator 1130. A wirelesspower receiving unit 1150 includes a communication unit 1151, anApplication Processor (AP) 1152, a Power Management Integrated Circuit(PMIC) 1153, a Wireless Power Integrated Circuit (WPIC) 1154, aresonator 1155, an InterFace Power Management (IFPM) IC 1157, a TravelAdapter (TA) 1158, and a battery 1159.

The communication unit 1110 communicates with the communication unit1151 based on a predetermined scheme, for example, a BLE scheme. Forexample, the communication unit 1151 of the wireless power receivingunit 1150 transmits a PRU dynamic signal having the data structure asshown in Table 3 to the communication unit 1110 of the wireless powertransmitting unit 1100. As described above, the PRU dynamic signal mayinclude at least one of voltage information, current information,temperature information, and alert information of the wireless powerreceiving unit 1150.

Based on the received PRU dynamic signal, a power value output from thepower amplifier 1120 may be adjusted. For example, when the overvoltage, the over current, and the over temperature are applied to thewireless power receiving unit 1150, a power value output from the poweramplifier 1120 is reduced. Further, when a voltage or current of thewireless power receiving unit 1150 is smaller than a preset value, apower value output from the power amplifier 1120 is increased.

Charging power from the resonator 1130 may be wirelessly transmitted tothe resonator 1155.

The WPIC 1154 rectifies the charging power received from the resonator1155 and performs DC/DC conversion. The WPIC 1154 drives thecommunication unit 1151 or charges the battery 1159 by using theconverted power.

Meanwhile, a wired charging terminal may be inserted into the traveladapter 1158. A wired charging terminal such as a 30-pin connector or aUniversal Serial Bus (USB) connector may be inserted into the traveladapter 1158, and the travel adapter 1158 receives power supplied froman external power source to charge the battery 1159.

The IFPM 1157 processes power applied from the wired charging terminaland outputs the processed power to the battery 1159 and the PMIC 1153.

The PMIC 1153 manages wirelessly received power, power received througha wire, and power applied to each of the components of the wirelesspower receiving unit 1150. The AP 1152 receives power information fromthe PMIC 1153 and controls the communication unit 1151 to transmit thePRU dynamic signal for reporting the power information.

Meanwhile, the travel adapter 1158 may be connected to a node 1156connected to the WPIC 1154. When the wired charging connector isinserted into the travel adapter 1158, a preset voltage, for example, 5V may be applied to the node 1156. The wireless power IC 1154 monitorsthe voltage applied to the node 1156 to determine whether the traveladapter is inserted.

FIG. 12A is a flowchart illustrating a control method of the wirelesspower receiving unit according to an embodiment of the presentinvention.

The wireless power receiving unit 1150 wirelessly receives chargingpower from the wireless power transmitting unit 1100 in step S1201. Thewireless power receiving unit 1150 detects whether the wired chargingterminal is inserted into the travel adapter in step S1203. For example,the wireless power receiving unit 1150 determines whether a voltageapplied to a back end of the travel adapter is a preset voltage value todetermine whether the wired charging terminal is inserted.

When it is determined that the wired charging terminal is inserted instep S1203, the wireless power receiving unit 1150 transmits a signalindicating the insertion of the wired charging terminal to the wirelesspower transmitting unit 1100 in step S1205. For example, the wirelesspower receiving unit 1150 transmits a PRU dynamic signal indicating TAdetect (3) in the PRU alert field of Table 3 to the wireless powertransmitting unit 1100. Alternatively, the wireless power receiving unit1150 may transmit the signal indicating the insertion of the wiredcharging terminal to the wireless power transmitting unit 1100 as asignal separate from the PRU dynamic signal. Meanwhile, the wirelesspower receiving unit 1150 may stop the wireless charging by releasingthe connection with the resonator 1155.

FIG. 12B is a flowchart illustrating a control method of the wirelesspower transmitting unit according to an embodiment of the presentinvention.

The wireless power transmitting unit 1100 wirelessly transmits chargingpower to the wireless power receiving unit 1150 in step S1211. Thewireless power transmitting unit receives the signal indicating theinsertion of the wired charging terminal into the travel adapter fromthe wireless power receiving unit 1150 in step S1213. When receiving thesignal indicating the insertion of the wired charging terminal in stepS1213, the wireless power transmitting unit 1100 controls an amount ofthe charging power in step S1215. For example, the wireless powertransmitting unit 1100 performs a control such that the charging poweris not transmitted by adjusting the amount of the charging power to 0.

According to the above description, when the wireless power receivingunit 1150 performs the wired charging, the wireless charging is stoppedand the over current is prevented from being applied.

FIG. 13 is a flowchart illustrating operations of the wireless powertransmitting unit and the wireless power receiving unit according to anembodiment of the present invention.

The wireless power transmitting unit 1100 transmits a charginginitiation command signal to the wireless power receiving unit 1150 instep S1301. In response to the signal, the wireless power receiving unit1150 performs the wireless charging by controlling a load switch to bein an on state in step S1302. The wireless power receiving unit 1150transmits the PRU dynamic signal in step S1303 and the wireless powertransmitting unit 1100 receives and analyzes the PRU dynamic signal instep S1304. Accordingly, the wireless power transmitting unit 1100identifies information such as the voltage, current, temperature of thewireless power receiving unit 1150 or wireless charging environmentchange such as the wired charging terminal insertion.

Meanwhile, the user may insert the wired charging terminal into thewireless power receiving unit 1150 and the wireless power receiving unit1150 detects the insertion in step S1305. The wireless power receivingunit 1150 determines whether wired or wireless power is provided in stepS1306. When neither the wired and wireless power are provided in stepS1306, the wireless power transmitting unit 1100 may enter the low powermode in step S1307. When it is determined that both the wired chargingand the wireless charging are performed in step S1306, the IFPM 1157 ofthe wireless power receiving unit 1150 stops the wireless charging byreleasing the connection with the resonator 1155 in step S1308.

The wireless power receiving unit 1150 outputs wired charging terminalinsertion detection (=TA (Travel Adapter) detection) to thecommunication unit 1151 in step S1309 and the communication unit 1151transmits a wired charging terminal insertion detection (=TA detection)signal to the wireless power transmitting unit 1100 in step S1310. Thewireless power transmitting unit 1100 controls the charging power inaccordance with the wired charging terminal insertion detection signalin step S1311. For example, the wireless power transmitting unit 1100performs a control such that the wireless charging is stopped byadjusting the charging power to 0.

The wireless power transmitting unit 1100 instructs non-reception ofpower in step S1312 and transmits a load switch off signal to thewireless power receiving unit 1150 in step S1313. The wireless powerreceiving unit 1150 receives the load switch off signal to control aload switch to be in an off state in step S1314.

The wireless power receiving unit 1150 periodically transmits the PRUdynamic signal in step S1315. The wireless power transmitting unit 1100receives and analyzes the PRU dynamic signal in step S1316.

Meanwhile, the wireless power receiving unit 1150 detects that the wiredcharging terminal insertion has been released in step S1317. Forexample, the wireless power receiving unit 1150 detects the release ofthe wired charging terminal insertion by detecting a change in a voltageapplied to a back end of the travel adapter 1158. The wireless powerreceiving unit 1150 transmits a wired charging terminal insertionrelease detection signal to the wireless power transmitting unit 1100 instep S1318. For example, the wireless power receiving unit 1150transmits the wired charging terminal insertion release detection signalas the PRU dynamic signal or a single signal. The wireless powertransmitting unit 1100 detects the release of the wired chargingterminal insertion from the wireless power receiving unit 1150 byanalyzing the PRU dynamic signal or the single signal in step S1319.

The wireless power transmitting unit 1100 transmits a load switch onsignal to the wireless power receiving unit 1150 in step S1320 and thewireless power receiving unit 1150 receives the load switch on signal tocontrol the load switch to be in the on state in step S1321. Meanwhile,the wireless power transmitting unit 1100 performs the wireless chargingby controlling the charging power again and the wireless power receivingunit 1150 performs the wireless charging by controlling the load switchto be in the on state.

According to the above description, the wireless power transmitting unit1100 detects the insertion or removal of the wired charging terminalinto/from the wireless power receiving unit 1150. The wireless powertransmitting unit may prevent power waste and over power from beingapplied to the wireless power receiving unit 1150 by controlling thecharging power according to the insertion or the removal of the wiredcharging terminal.

FIG. 14 is a block diagram of the communication unit and peripheralcomponents of the wireless power receiving unit according to anembodiment of the present invention.

As illustrated in FIG. 14, the communication unit 1151 of the wirelesspower receiving unit 1150 includes a Random Access Memory (RAM) 1161 anda Read Only Memory (ROM) 1162. The communication unit 1151 communicateswith the wireless power transmitting unit 1100 based on a predeterminedscheme, for example, a BLE scheme. Accordingly, a stack of apredetermined communication scheme, for example, a BLE stack is loadedto the RAM 1161 of the communication unit 1151. The communication unit1151 receives the BLE stack from the AP 1152 to load the BLE stack tothe RAM 1161. As described above, a mode in which the communication unit1151 receives a stack of a predetermined communication scheme from theAP 1152 to load the stack to the RAM 1161 is referred to as a Non StandAlone (NSA) mode.

Meanwhile, the wireless power receiving unit 1150 may be arranged on thewireless power transmitting unit 1100 after the battery 1159 isdischarged. Since the battery 1159 of the wireless power receiving unit1150 is discharged, the AP 1152 cannot be driven.

The wireless power receiving unit 1150 may drive the communication unit1151 of the wireless power receiving unit 1150 by receiving a powerdetection beacon. However, as described above, since the AP 1152 is notdriven, the communication unit 1151 cannot receive a stack of apredetermined communication scheme from the AP 1152. The communicationunit 1151 may store the stack of the predetermined communication schemein the ROM 1162 and communicate with the wireless power transmittingunit 1100 by using the stack of the predetermined communication schemestored in the ROM 1162. As described above, a mode in which thecommunication unit 1151 performs the communication by using the stack ofthe predetermined communication scheme stored in the ROM 1162 isreferred to as a Stand Alone (SA) mode.

FIG. 15A is a flowchart illustrating a control method of the wirelesspower receiving unit according to an embodiment of the presentinvention.

The wireless power receiving unit 1150 turns off power by thedischarging the battery 1159 in step S1501. The wireless power receivingunit 1150 receives first power which can drive the communication unit1151 from the wireless power transmitting unit 1100 in step S1503 anddrives the communication 1151 by using the first power. The wirelesspower receiving unit 1150 enters the SA mode, for example, load the BLEstack from the ROM 1162 in step S1505. The communication unit 1151 ofthe wireless power receiving unit 1150 communicates with the wirelesspower receiving unit 1100 by using the loaded BLE stack in step S1507.

FIG. 15B is a flowchart illustrating a control method of a wirelesspower receiving unit according to an embodiment of the presentinvention.

The wireless power receiving unit 1150 performs the wireless chargingwhile operating in the SA mode. Based on the wireless charging, thewireless power receiving unit 1150 turns on the battery 1159 and the AP1152 in step S1511. The wireless power receiving unit 1150 switches theSA mode to the NSA mode in step S1513. The wireless power receiving unit1150 transmits a mode transition detection signal to the wireless powertransmitting unit 1100 in step S1515. The wireless power receiving unit1150 loads the BLE stack from the AP 1152 in step S1517 and reinitiatescommunication with the wireless power transmitting unit 1100 in stepS1519.

FIG. 15C is a flowchart illustrating a control method of the wirelesspower transmitting unit according to an embodiment of the presentinvention.

The wireless power transmitting unit 1100 transmits charging power tothe wireless power receiving unit 1150 in step S1521. The wireless powertransmitting unit 1100 receives the transition detection signal from theSA mode to the NSA mode from the wireless power receiving unit 1150 instep S1523. The wireless power transmitting unit 1100 stands by for apreset waiting time in step S1525. For example, when the wireless powertransmitting unit 1100 does not receive a signal from the wireless powerreceiving unit 1150 for one second, the wireless power transmitting unit1100 may be set to exclude the wireless power receiving unit 1150 fromthe wireless power network. However, when the wireless powertransmitting unit 1100 receives the transition detection signal from theSA mode to the NSA mode from the wireless power receiving unit 1150, thewireless power transmitting unit 1100 does not exclude the wirelesspower receiving unit 1150 from the wireless power network even thoughthe signal is not received from the wireless power receiving unit 1150for the preset waiting time.

When the preset waiting time arrives, the wireless power transmittingunit 1100 communicates with the wireless power receiving unit 1150 againin step S1527.

According to the above description, when the wireless power receivingunit 1150 switches the SA mode to the NSA mode, the communication withthe wireless power transmitting unit 1100 may be disconnected for apredetermined time. However, even though the signal is not received fromthe wireless power receiving unit 1150 for the preset waiting time, thewireless power transmitting unit 1100 does not exclude the wirelesspower receiving unit 1150 from the wireless power network by receivingthe transition signal from the SA mode to the NSA mode. Accordingly, anunintended error by the mode transition of the wireless power receivingunit can be prevented.

According to the above description, the wireless power transmitting unit1100 detects a change in a wireless power transmission environment suchas the mode transition and does not exclude the wireless power receivingunit 1150 from the wireless power network.

FIGS. 16A and 16B are flowcharts of control methods of the wirelesspower receiving unit and the wireless power transmitting unit accordingto embodiments of the present invention.

Referring to FIG. 16A, the wireless power receiving unit 1150 detects anerror in step S1601. The error refers to generation of at least one ofover current, over voltage, and over temperature of the wireless powerreceiving unit 1150. The wireless power receiving unit 1150 transmits anerror signal indicating the generation of the error to the wirelesspower transmitting unit 1100 in step S1603.

The wireless power receiving unit 1150 determines whether the errorstate is released in step S1605. When it is determined that the errorstate is released in step S1605, the wireless power receiving unit 1150transmits a charging restart request signal to the wireless powertransmitting unit 1100 in step S1607. The wireless power receiving unit1150 receives charging power from the wireless power transmitting unit1100 to restart the charging in step S1609. The charging restart requestsignal may be written as restart request (1) in the PRU alert field ofthe PRU dynamic signal of Table 3 and transmitted. Alternatively, thecharging restart request signal may be transmitted as a single signal.

Referring to FIG. 16B, the wireless power transmitting unit 1100transmits charging power to the wireless power receiving unit 1150 instep S1611. It is assumed that the charging power transmitted to thewireless power receiving unit 1150 by the wireless power transmittingunit 1100 has a first power value. Meanwhile, the wireless powertransmitting unit 1100 determines if an error signal is received fromthe wireless power receiving unit 1150 in step S1613. When the errorsignal is received in step S1613, the wireless power transmitting unit1100 adjusts the charging power to a second power value from the firstpower value in step S1615. The second power value may be smaller thanthe first power value, and charging power having a relatively smallvalue may be transmitted until the error state is released.

Meanwhile, the wireless power transmitting unit 1100 determines if thecharging restart request signal is received from the wireless powerreceiving unit 1150 in step S1617. When the charging restart requestsignal is received in step S1617, the wireless power transmitting unit1100 adjusts again the charging power to the first power value from thesecond power value and transmits the charging power to the wirelesspower receiving unit 1150 in step S1619. Accordingly, when the errorstate is released, the charging power is restored and then transmitted.

According to the above description, the wireless power transmitting unit1100 can detect the wireless power transmission environment change suchas the error state generation and the error state release, and controlsthe charging power value according to the detection, so as toefficiently perform the wireless charging.

FIG. 17 illustrates a concept for describing a cross-connection. In FIG.17, a first wireless power transmitting unit TX1 and a second wirelesspower transmitting unit TX2 are disposed. Further, a first wirelesspower receiving unit RX1 is disposed on the first wireless powertransmitting unit TX1, and a second wireless power receiving unit RX2 isdisposed on the second wireless power transmitting unit TX2. Here, thefirst wireless power transmitting unit TX1 transmits power to the firstwireless power receiving unit RX1 located on or near the first wirelesspower transmitting unit TX1. In addition, the second wireless powertransmitting unit TX2 transmits power to the second wireless powerreceiving unit RX2 located on or near the second wireless powertransmitting unit TX2. Accordingly, it is preferable that the firstwireless power transmitting unit TX1 performs communication with thefirst wireless power receiving unit RX1 and the second wireless powertransmitting unit TX2 performs communication with the second wirelesspower receiving unit RX2. However, according to an increase in acommunication distance, the first wireless power receiving unit RX1 maysubscribe to a wireless power network controlled by the second wirelesspower transmitting unit TX2, and the second wireless power receivingunit RX2 may subscribe to a wireless power network controlled by thefirst wireless power transmitting unit TX1. This is referred to ascross-connection.

Accordingly, a problem may occur in which the first wireless powertransmitting unit TX1 transmits power requested by the second wirelesspower receiving unit RX2, not power requested by the first wirelesspower receiving unit RX1. When a capacity of the second wireless powerreceiving unit RX2 is greater than that of the first wireless powerreceiving unit RX1, over capacity power may be applied to the firstwireless power receiving unit RX1, which causes a problem. Further, whenthe capacity of the second wireless power receiving unit RX2 is lessthan that of the first wireless power receiving unit RX1, a problemoccurs in which the first wireless power receiving unit RX1 may receivepower less than its charging capacity.

Accordingly, the wireless power transmitting unit is required to excludethe cross-connected wireless power receiving units from the wirelesspower network.

FIG. 18 illustrates a concept for describing an arrangement relationbetween the wireless power transmitting unit and the wireless powerreceiving unit according to an embodiment of the present invention.

In FIG. 18, a first wireless power transmitting unit PTU#1, a secondwireless power transmitting unit PTU#2, and a third wireless powertransmitting unit PTU#3 are arranged. Further, a first wireless powerreceiving unit PRU#1 (or RX1), a second wireless power receiving unitPRU#2, a third wireless power receiving unit PRU#3, a fourth wirelesspower receiving unit PRU#4, a fifth wireless power receiving unit PRU#5,and a sixth wireless power receiving unit PRU#6 are arranged.Particularly, the first wireless power receiving unit PRU#1 and thesecond wireless power receiving unit PRU#2 are located within achargeable range of the first wireless power transmitting unit PTU#1.Further, the third wireless power receiving unit PRU#3 and the fourthwireless power receiving unit PRU#4 are located within a chargeablerange of the second wireless power transmitting unit PTU#2. In addition,the fifth wireless power receiving unit PRU#5 and the sixth wirelesspower receiving unit PRU#6 are located within a chargeable range of thethird wireless power transmitting unit PTU#3.

The first wireless power transmitting unit PTU#1 forms communicationconnections with the first wireless power receiving unit PRU#1 and thesecond wireless power receiving unit PRU#2 located within the chargeablerange. However, a communication distance of the first wireless powertransmitting unit PTU#1 may be relatively wider than the chargeablerange. The first wireless power transmitting unit PTU#1 may formcommunication connections with the third wireless power receiving unitPRU#3 and the fourth wireless power receiving unit PRU#4 arrangedoutside the chargeable range.

When the first wireless power transmitting unit PTU#1 formscommunication connections with the third wireless power receiving unitPRU#3 and the fourth wireless power receiving unit PRU#4, the firstwireless power transmitting unit PTU#1 may apply a sum of first power,second power, third power, and fourth power to be transmitted to thefirst wireless power receiving unit PRU#1 to the fourth wireless powerreceiving unit PRU#4, respectively. Accordingly, the first wirelesspower transmitting unit PTU#1 may transmit the sum of the first power,the second power, the third power, and the fourth power, not merely asum of the first power and the second power, to the first wireless powerreceiving unit PRU#1 and the second wireless power receiving unit PRU#2.Accordingly, the first wireless power transmitting unit PTU#1 wastespower, and the first wireless power receiving unit PRU#1 and the secondwireless power receiving unit PRU#2 are applied over power.

Accordingly, a solution is required whereby the first wireless powertransmitting unit PTU#1 should disconnect the communication connectionswith the third wireless power receiving unit PRU#3 and the fourthwireless power receiving unit PRU#4. Further, a technique by which thefirst wireless power transmitting unit PTU#1 determines that the thirdwireless power receiving unit PRU#3 and the fourth wireless powerreceiving unit PRU#4 are cross-connected wireless power receiving unitsis also required. Hereinafter, based on various embodiments, aconfiguration of determining a cross-connected wireless power receivingunit will be described.

FIG. 19 is a flowchart illustrating a method of determining across-connected wireless power receiving unit according to an embodimentof the present invention. FIG. 20A is a graph showing a change intransmission power of a wireless power transmitting unit, and FIG. 20Bis a graph showing a change in a voltage of a wireless power receivingunit according to an embodiment of the present invention.

The wireless power receiving unit receives a signal from one or morewireless power receiving units in step S1901. For example, the wirelesspower transmitting unit receives the advertisement signal described inconnection with FIG. 4, such as a PTU searching signal, from the one ormore wireless power receiving units.

The wireless power transmitting unit performs a first wireless powerreceiving unit classification step based on an intensity of theadvertisement signal received from the wireless power receiving unit instep S1903. For example, the wireless power transmitting unit determineswhether a Received Signal Strength Indicator (RSSI) of each of theadvertisement signals received from the one or more wireless powerreceiving units is greater than a preset reference value. The wirelesspower transmitting unit determines that the wireless power receivingunit having transmitted the advertisement signal greater than the presetreference value is a wireless power receiving unit to be connected basedon the first classification step.

In another embodiment, the wireless power transmitting unit may identifyall RSSIs of the advertisement signals received from the one or morewireless power receiving units. The wireless power transmitting unitidentifies a minimum RSSI, sets an offset based on the minimum RSSI, andsets a determination range of the wireless power receiving unit to becommunicated with. The wireless power transmitting unit determines awireless power receiving unit having transmitted the advertisementsignal having an RSSI within the determination range of the wirelesspower receiving unit to be communicated with as the wireless powerreceiving unit to be communicated with based on the first classificationstep.

Meanwhile, the wireless power transmitting unit changes an amount ofpower transmitted to the wireless power receiving unit in step S1905.For example, as illustrated in FIG. 20A, the wireless power transmittingunit may change an amount of transmitted power 2001 to a form of a sinewave based on ‘a’. The wireless power transmitting unit may change thetransmitted power 2001 according to a preset time period T. Meanwhile,the change of the sine wave of the transmitted power 2001 as illustratedin FIG. 20A is only an example.

The wireless power transmitting unit receives a report signal from thefirst classified wireless power receiving unit in step S1907. Thewireless power transmitting unit receives, for example, a PRU dynamicsignal from the wireless power receiving unit. As described above withreference to Table 3, the PRU dynamic signal may include information ona current value or a voltage value of the wireless power receiving unit.

The wireless power transmitting unit performs a second classificationstep based on the change in the voltage value of the wireless powerreceiving unit in step S1909. For example, the wireless powertransmitting unit determines whether a size of the voltage of thewireless power receiving unit has been changed in accordance with achange in a size of transmitted power. For example, the wireless powertransmitting unit may receive a report of a voltage size 2002 of thewireless power receiving unit as illustrated in FIG. 20B. In FIG. 20B,it is noted that the voltage size 2002 of the wireless power receivingunit has the form of a sine wave based on ‘b’, and particularly, ischanged on a period of T. The wireless power transmitting unit maydetermine the wireless power receiving unit of which the voltage size2002 is changed according to the T period as the wireless powerreceiving unit to be communicated with. Further, the wireless powertransmitting unit may determine that a wireless power receiving unithaving a voltage irrelevant to the change of the transmitted power isthe cross-connected wireless power receiving unit.

The wireless power transmitting unit disconnects the communicationconnection with the wireless power receiving unit determined to becross-connected in step S1911.

FIG. 21 is a flowchart illustrating a method of determining across-connected wireless power receiving unit according to anotherembodiment of the present invention. FIG. 22 is a graph showingintensities of signals from wireless power receiving units according toan embodiment of the present invention.

The wireless power transmitting unit receives a signal from one or morewireless power receiving units in step S2101. For example, the wirelesspower transmitting unit receives the advertisement signal described inconnection with FIG. 4, such as a PTU searching signal, from the one ormore wireless power receiving units.

The wireless power transmitting unit performs a first wireless powerreceiving unit classification step to group the wireless power receivingunits based on similarity of the intensities of the advertisementsignals received from the wireless power receiving units in step S2103.

The wireless power transmitting unit measures intensities of signalsfrom the wireless power receiving units as illustrated in FIG. 22. InFIG. 22, an x axis is time and a y axis is an RSSI. The wireless powertransmitting unit groups the wireless power receiving units based onRSSI similarity. Accordingly, the wireless power transmitting unitclassifies one or more wireless power receiving units into a firstgroup, a second group, and a third group.

Meanwhile, the wireless power transmitting unit changes an amount ofpower transmitted to the wireless power receiving unit in step S2105.The wireless power transmitting unit receives signals from the one ormore wireless power receiving units in step S2107. The wireless powertransmitting unit receives, for example, a PRU dynamic signal from thewireless power receiving unit. As described above with reference toTable 3, the PRU dynamic signal may include information on a currentvalue or a voltage value of the wireless power receiving unit.

The wireless power transmitting unit performs a second classificationstep based on the change in the voltage value of the wireless powerreceiving unit in step S2109. For example, the wireless powertransmitting unit determines that a group of the wireless powerreceiving units of which voltages are changed in accordance with thechange in the transmitted power are the wireless power receiving unitsto be communicated with. Further, the wireless power transmitting unitdetermines that the wireless power receiving units in the remaininggroups are the cross-connected wireless power receiving units anddisconnects the communication connection to these wireless powerreceiving units in step S2111.

FIG. 23 is a flowchart illustrating a method of determining across-connected wireless power receiving unit according to anotherembodiment of the present invention.

The wireless power transmitting unit receives signals from one or morewireless power receiving units in step S2301. For example, the wirelesspower transmitting unit receives the advertisement signal described inconnection with FIG. 4, such as a PTU searching signal, from the one ormore wireless power receiving units. Meanwhile, when the wireless powerreceiving unit transmits the advertisement signal, transmission outputinformation may be also transmitted. That is, the advertisement signalincludes transmission intensity information.

The wireless power transmitting unit receives the advertisement signaland determines a reception intensity, a Link Quality Indicator (LQI), oran RSSI. The wireless power transmitting unit calculates a path lossbased on the transmission output information and the reception intensityof the advertisement signal in step S2303. The wireless powertransmitting unit determines a distance between the wireless powertransmitting unit and the wireless power receiving unit through thecalculated path loss and Equation (1) below.

$\begin{matrix}{L = {20\; {\log_{10}\left( \frac{\lambda}{4\; \pi \; d} \right)}}} & (1)\end{matrix}$

In Equation (1), L denotes a path loss, λ denotes a wavelength, and ddenotes a distance between the wireless power transmitting unit and thewireless power receiving unit.

The wireless power transmitting unit performs a first classificationstep based on the calculated path loss in step S2305. For example, thewireless power transmitting unit determines that the wireless powerreceiving unit having a distance from the wireless power transmittingunit which is within a preset distance is the wireless power receivingunit to be communicated with.

Meanwhile, the wireless power transmitting unit changes an amount ofpower transmitted to the wireless power receiving unit in step S2307.The wireless power transmitting unit receives report signals from theone or more wireless power receiving units in step S2309. The wirelesspower transmitting unit receives, for example, a PRU dynamic signal fromthe wireless power receiving unit. As described above with reference toTable 3, the PRU dynamic signal may include information on a currentvalue or a voltage value of the wireless power receiving unit.

The wireless power transmitting unit performs a second classificationstep based on the change in the voltage value of the wireless powerreceiving unit in step S2311. For example, the wireless powertransmitting unit determines that the wireless power receiving unit ofwhich the voltage is changed in accordance with the change in thetransmitted power is the wireless power receiving unit to becommunicated with, determines the wireless power receiving units in theremaining groups as the cross-connected wireless power receiving units,and disconnects the communication connection in step S2313.

Meanwhile, in the above description, the amount of the transmitted poweris changed in a case where the second step classification is performed.In another embodiment of the present invention, the wireless powertransmitting unit may determine that the wireless power receiving unitwhich receives a signal within a preset time after detection of a loadchange is the wireless power receiving unit to be communicated with. Thewireless power transmitting unit receives, for example, a PTU searchingsignal or an advertisement signal from the wireless power receivingunit. The wireless power transmitting unit determines that the wirelesspower receiving unit having received the PTU searching signal or theadvertisement signal within a preset time is the wireless powerreceiving unit to be communicated with. The wireless power transmittingunit determines that the wireless power receiving unit having receivedthe PTU searching signal or the advertisement signal after the presettime after the detection of the load change is the cross-connectedwireless power receiving unit and disconnects the communicationconnection.

Meanwhile, the wireless power transmitting unit according to anembodiment of the present invention may solely determine that thewireless power receiving unit having received the signal within thepreset time after the detection of the load change is the wireless powerreceiving unit to be communicated with. For example, the wireless powertransmitting unit may determine whether the wireless power receivingunit is the wireless power receiving unit to be communicated withdirectly based on whether a difference between a load change detectiontime and a time of signal reception from the wireless power receivingunit is within a preset time without performing the first classificationstep based on the signal intensity from the wireless power receivingunit. The aforementioned disconnection of the communication connectionmay be applied to a case where there is no load change detection.

Although it has been described in the example above that the wirelesspower receiving unit receives the PTU searching signal or theadvertisement signal within the preset time after the load changedetection, the order may be changed in such a manner that the loadchange is detected within the preset time after the reception of thesignal, but the cross-connection detecting method is the same.

Further, determining the wireless power receiving unit to be connectedin consideration of the load change may be performed alone without thedetermination step based on the signal intensity.

Meanwhile, the wireless power transmitting unit may have difficulty indetecting the load change of a wireless power receiving unit having asmall size or a device having small power consumption. In this event,the wireless power receiving unit provides additional information to thewireless power transmitting unit in communication, so that determiningthe wireless power receiving unit to be communicated with through theload change detection by the wireless power transmitting unit may beexcluded. The additional information may be category informationclassified according to power consumption, or a size of the wirelesspower receiving unit, or information indicating whether the wirelesspower transmitting unit can detect the load change.

More specifically, when the wireless power transmitting unit receivesthe PTU searching signal of the wireless power receiving unit, thewireless power transmitting unit recognizes category information of thewireless power receiving unit included in the searching signal. Thecategory information may have a value of one of a Category 1 to Category5 according to a type of the wireless power receiving unit.

TABLE 5 Wireless power receiving unit category Wireless power receivingunit type category 1 Bluetooth headset category 2 feature phone category3 smart phone category 4 tablet category 5 laptop

When the recognized category information corresponds to Category 2 toCategory 5, the wireless power transmitting unit determines that theload change detection is possible. Then, the wireless power transmittingunit determines whether the reception search is performed within apreset time after the load change detection. When the reception searchis performed within the preset time, the wireless power transmittingunit determines that the wireless power receiving unit is the wirelesspower receiving unit to be communicated with and performs thecommunication. Further, when there is no load change detection or theload change is detected after the preset time, the wireless powertransmitting unit determines that the wireless power receiving unit isnot the wireless power receiving unit to be communicated with anddisconnects the communication.

Meanwhile, when the category information recognized by the wirelesspower transmitting unit corresponds to Category 1, the wireless powertransmitting unit determines that the load change detection is notpossible and thus performs the determination of the wireless powerreceiving unit to be communicated with regardless of the load changedetection.

A reference of the category information to determine whether the loadchange detection can be performed by the wireless power transmittingunit may be preset by the wireless power transmitting unit or receivedfrom the wireless power receiving unit through the communication.

Meanwhile, although it has been described that the wireless powerreceiving unit to be communicated with is determined based on thecategory of the wireless power receiving unit, Table 6 below may be usedas the reference to determine the wireless power receiving unit to becommunicated with.

Specifically, when the wireless power transmitting unit receives the PTUsearching signal of the wireless power receiving unit, the wirelesspower transmitting unit detects load detection indication bitinformation of the wireless power receiving unit included in thesearching signal. The load detection indication bit information may havea value of three bits, such as “000”, “001”, “010”, “011”, “100”, and“101”, according to a type of the wireless power receiving unit.

TABLE 6 load detection indication bit (bit) Type of wireles powerreceiving unit 000 Device of which load change cannot be detected 001Wireless power receiving unit of category 1 (for example, Bluetoothheadset) 010 Wireless power receiving unit of category 2 (for example,feature phone) 011 Wireless power receiving unit of category 3 (forexample, smart phone) 100 Wireless power receiving unit of category 4(for example, tablet) 101 Wireless power receiving unit of category 5(for example, laptop)

For example, when the load detection indication bit corresponds to“000”, it refers to a device of which the load change cannot be detectedregardless of the category of the wireless power receiver. Accordingly,even in a case of a smart phone having Category information 3 of thewireless power receiving unit, when the load detection indication bitincluded in the searching signal corresponds to “000”, the device isdetermined as not being subject to be communicated with and thecommunication is disconnected.

Various embodiments of the present invention provide a wireless powertransmitting unit and a control method thereof which determine awireless power receiving unit forming a cross-connection and exclude thedetermined wireless power receiving unit. Further, various embodimentsof the present invention provide a wireless power receiving unit and acontrol method thereof in which a wireless power transmitting unitdetermines a wireless power receiving unit forming a cross-connection.

Accordingly, it is possible to prevent the waster power of the wirelesspower transmitting unit due to cross-connection. Further, a condition inwhich over power is applied to wireless power receiving units due tocross-connection can be prevented.

While the present invention has been shown and described with referenceto certain embodiments thereof, it will be understood by those skilledin the art that various changes in form and details may be made thereinwithout departing from the spirit and scope of the present invention asdefined by the appended claims. Therefore, various modifiedimplementations can be made without departing from the substance of thepresent invention claimed in the appended claims, and the modifiedimplementations should not be construed separately from the technicalidea or concept of the present invention.

What is claimed is:
 1. A method for controlling a wireless powertransmitter configured to transmit power to a wireless power receiver,the method comprising: applying a detection power for detecting a changein a load impedance of the wireless power transmitter caused by aplacement of the wireless power receiver; detecting the change in theload impedance of the wireless power transmitter; receiving a firstsignal from the wireless power receiver; determining whether a receptionintensity of the first signal is greater than a threshold; andtransmitting a second signal to the wireless power receiver based ondetecting the change in the load impedance and determining whether thereception intensity of the first signal is greater than the threshold.2. The method of claim 1, wherein the second signal is arranged suchthat the wireless power receiver performs a joining operation totransmit the power.
 3. The method of claim 1, wherein determiningwhether the reception intensity of the first signal is greater than thethreshold comprises: identifying a minimum reception intensity; settinga determination range based on the minimum reception intensity; anddetermining whether the reception intensity of the first signal iswithin the determination range.
 4. The method of claim 3, whereinidentifying the minimum reception intensity comprises: identifying theminimum reception intensity from among first signals received from aplurality of wireless power receivers.
 5. A wireless power transmitterconfigured to transmit power to a wireless power receiver, the wirelesspower transmitter comprising: a resonator configured to transmitwireless power to the wireless power receiver; a controller configuredto apply a detection power for detecting a change in a load impedance ofthe wireless power transmitter caused by a placement of the wirelesspower receiver to the resonator, and detect the change in the loadimpedance of the wireless power transmitter; and a wirelesscommunication unit configured to receive a first signal from thewireless power receiver, wherein the controller is further configured todetermine whether a reception intensity of the first signal is greaterthan a threshold, and control the wireless communication unit totransmit a second signal to the wireless power receiver if the firstsignal is greater than the threshold.
 6. The wireless power transmitterof claim 5, wherein, the second signal is arranged such that thewireless power receiver performs a joining operation to transmit thepower.
 7. The wireless power transmitter of claim 5, wherein thecontroller is further configured to: identify a minimum receptionintensity; set a determination range based on the minimum receptionintensity; and determine whether the reception intensity of the firstsignal is within the determination range.
 8. The wireless powertransmitter of claim 7, wherein the controller is further configured to:identify the minimum reception intensity from among first signalsreceived from a plurality of wireless power receivers.